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PLANT ANATOMY






Anatomy  deals with the study of gross internal structure
...

On the basis of cell division; plant tissue is of two types:
A
...
Permanent tissues

Meristematic Tissue






Made up of group of immature cells that are preparing to divide or are in continuous state of
division
...

Meristem are ultimate source of all tissue in plant
...


On the basis of origin and development:
1
...

Give rise to …………………………………
Plant embryo truly represents this kind of meristem
...
Emb]
2
...

Function …………………………………………………………………
...

3
...

Function …………………………………………………………………
...


B
...
Apical meristems:
Location: at apices of
stem and root
...

2
...

Originate from the
apical
meristems
during development
[Ind Emb, IOM
1997]
...

Figure: Meristem based on position


...
Lateral meristem:
Position: Present along the lateral sides of stem and roots
...

Example: intrafascicular, interfascicular cambium and cork cambium (phellogen)
...
Apical cell theory (By Nageli)
Statement: ………………………………………………………………………
...

2
...


Figure: Types of Histogen on Shoot apex
Plerome (central core): form stele
...


b
...


Periblem (several layer surrounding plerome): form hypodermis, cortex and
endodermis
...

In case of monocot; one more histogen, i
...
, Calyptrogen is present
forms root cap

Note:


3
...
e
...

Tunica forms 
Corpus forms
Applicable
4
...

Cells of this region normally remain inactive and serve as reservoir to meristematic zone
...
C
...

1
...

2
...

3
...

PERMANENT TISSUES



Formed as a result of division and differentiation in meristematic tissues
...

Permanent Tissue

Simple Permanent Tissue

Complex Permanent Tissue

Special PermanentTissue
Glandular Tissue

Xylem

Phloem
Laticiferous Tissue

Parenchyma
Collenchyma

Sclerenchyma

Simple
Permanent Tissues




Formed of structurally similar cells (homogenous group of cells) that perform a common
function
...
[IE 2005]

Quick Digest:

distributed tissue in plant is parenchyma
...

Number of facets in parenchymal cell is 14
...

Location in plant body  most abundant tissue; present in all organs of the plant, e
...

roots, stems, leaves, flowers, fruits and seeds
...

Aerenchyma: Parenchyma with air sacs, found in hydrophytes like Eichhornia for buoyancy
...
of
chloroplasts is present)
...


Collenchyma (=Living mechanical tissue)

It is living mechanical tissue
...


Sometimes collenchyma develops chloroplasts and helps in photosynthesis
...


Uneven Deposition
of pectocellulose

No intracellular space

Figure: Collenchyma


Based upon the thickening of the cell walls, collenchyma is of three types :
1
...
g
...

2
...
g
...
Lacunate or tubular type: Thickenings occur in cell wall bordering the intercellular space,
with intercellular space, e
...
hypodermis of cucurbita stem
...

Pits are non-lignified area on lignified wall
...
[MOE 2009, IOM 2006]  Main
function of sclerenchyma is to provide the mechanical strength
...
e
...


Branched pits
Figure: Fibre and Sclereids

Sclerenchyma fibres:





Shape of cell ……………………………………………………………………………………………
Cell wall and lumen ……………………………………………………………………………………………
Main function ……………………………………………………………………………………………
Fibre obtained from any other part than xylem are called extraxylary or bast fibre (can be
knitted)
...
g
...
g
...


Complex permanent tissue



A complex tissue is made up of structurally dissimilar cells performing a common function
...
e
...
[NEET
2019]
It forms bulk of root and stem of vascular plants
...

Composed up of 4 types of cell
...


Out of four element; xylem (wood) parenchyma is
only living [MOE] and remaining three i
...
, vessels,

Vessel elements

▪ Vessels and

tracheids
elements because they conduct

together are

called tracheary

▪ Functional part of xylem is called Hadrome (by
Haberlandt)
...

………………………………………………………………………………………………………………………………………
…………………………………………………………………………………………………………………………………

Function…………………………………………………………………

Distribution  …………………………………………………………………

Most primitive type of conducting elements in xylem
...


Quick Digest:
Borde



red pits is common in metaxylem of Gymnosperms
Vessel differ from tracheid in having broader lumen




"Tyloses" are balloon like ingrowths through pits in the lumens of vessels and tracheids which
plug them
...




Vessels or Trachea:

Structure ……………………………………………………………………………………………………………………
...

Diameter of lumen of vessels > tracheids
...

Besides, vessels are absent in stem and leaves of Yucca and Dracaena
...
[MOE 2014]

Winteraceae,
Net like thickening

Xylem parenchyma:

Parenchyma cells associated with xylem helps in storage and lateral conduction of water and
minerals
...

Types of xylem:

Based on origin; 2 types:
Protoxylem



Metaxylem

First formed primary xylem from procambium
during formation of primary plant body
...


Vessels and tracheids are bigger and
has reticulate or pitted or spiral
thickening on their secondary wall
...

Based on position of protoxylem:
1
...
g
...
[BPKIHS
2001, IOM 1999]
2
...
g
...
@ S End
3
...
e
...
g
...
Endarch xylem (Centrifugal
development), B
...
Mesarch xylem
(=Both centripetal and centrifugal development

Phloem or Leptome


Function  conduction/translocation of food/organic solute (sucrose and protein) in both
upward and downward direction (=bidirectional)
...

1
...
Companion cells

Living cells with cellulosic wall

3
...
Phloem fibres

Dead cell with lignified wall

Sieve elements:

Sieve elements in angiosperms  sieve tubes

Sieve tube  are made up of sieve cells arranged one after other in distinct linear rows and have
perforated sieve plate (oblique or transverse perforated septa) on their end walls
...


In gymnosperm and pteridophyte, sieve elements are  sieve cells
...


Callose controls the translocation of food during winter and get dissolved during summer
(active period)
...


Cell wall of sieve tube and sieve cell have simple pit
...


Leptome;

▪ Activity of

xylem

is

unidirectional whereas
activity of
phloem is bidirectional
...

▪ Starch grain

is

absent

in

companion cells
for which it is
dependent on sieve tube
...
TS of phloem, B
...


Companion cells and seive tubes are originated from same mother cell so called sister cells
...


Companion cells occur only in Angiosperms and are absent in the phloem of Pteridophyte and
Gymnosperm
...


Daucus (carrot) has many companion cells associated with one sieve tube
...


Quick Digest


Mammalian RBCs



Sieve tube is charac



teristic of
Angiosperm [NEET 2019] Sieve cells
are present in Gymnosperm &



Pteridophyte
...


Phloem parenchyma:

Parenchymal cells associated with phloem and that helps in storage and lateral conduction of
food
...

Phloem fibres:

Commonly called bast fibres (=to bind) because phloem fibres are used in binding articles
...


They provide mechanical support
...


SPECIAL TISSUES





These tissue perform special function in the plants, e
...
secretion of resin gum, oil and latex
...

a
...
g
...

b
...
g
...
Schizolysigenous cavity: is formed by both separation and disintegration of cells, e
...

protoxylem cavity of maize

Figure: A
...
Lysigenous (in Citrus) and C
...
e
...


Glandular tissues

Two types of glandular tissue : External glands and Internal glands
External glands:

Location epidermis of stem and leaves as glandular outgrowth  Example:
Glandular hair: Present in epidermal layers of leaves e
...
stinging hairs in Urtica dioica
...

Digestive glands or Enzyme secreting glands: present in insectivorous plants e
...
Drosera
(Sundew)
...
the internal glands secrete a volatile oil into lysigenous
cavities
...


Water secreting glands (Hydathodes = water stomata): These excrete water in the form of
drops from tip and margins of leaves of some herbaceous plants that generally grow in humid
places, e
...
Colocasia, Tropaeoleum
...
Below the aperture is an air cavity, below
which a loose tissue called epithem is present
...


Latex may be watery (e
...
banana), milky (e
...
euphorbia, banyan) or colored (e
...
poppy)

Latex cells: cells do not fuse together to form a network, e
...
, Calotropis, Nerium, Euphorbia,
Ficus
...
g
...


Quick Digest:

Latex of poppy plant is source of alkaloid Opium or Morphine

Natural rubber is obtained from Hevea brasiliensis

Latex of Papaya contain enzyme papain (digestive enzyme)

Insectivorous plant digest insect to obtain nitrogen from their chitinous exoskeleton
...
Epidermal tissue system
...
Fundamental or ground tissue system
...
Vascular or fascicular tissue system
...


Normally  uniseriate (single layer) and living and without chloroplasts
...

Epidermal cells with chloroplast  Guard cells

Root epidermis is termed as epiblema or rhizodermis or piliferous layer, which develop
unicellular root hairs in the zone of maturation
...


Epidermal cells may have deposition of cutin or suberin
...
Motor cells/ bulliform (bubble-like) cells [BPKIHS 2002]
Location …………………………………………………………
...

2
...

Stomata  surrounded by guard cells so can be closed and can be opened
...
[Details of stomata is given in plant physiology]
Lenticels found only in some woody stem and root like pneumatophore (known as
pneumathode in root)
...


Trichomes:
Represents various unicellular and multicellular appendages that originate from epidermal
cells
...


Ground (Fundamental) Tissue System

Main body of plant is made up of ground system (= all tissue except epidermal tissue and
vascular tissue fall under ground system)

Except monocot stems ground tissue is differentiated into an outer cortex and central pith
...


Absent in root

Monocot stem ………………………………………………  Dicot
stem…………………………………………………
...


Cells are thin-walled and parenchymatous

General cortex provides mechanical support and stores food material
...
S
...

Cells:…………………………………………………………………………………………………………………………
...
[NEET 2018]
A distinct endodermis is a constant feature of roots of all plants
...

Passage cells help in passage of water from cortex to xylem
...
[IOM 2008]

heterogenous pericycle is present in sunflower
...


In angiosperms pericycle give rises to lateral roots so they are endogenous in origin
...


Extensions are called pith rays or medullary rays
...


The varying number of vascular bundles formed inside the stele constitute vascular tissue
system
...


Vascular bundles in dicotyledonous stem and in roots of dicots as well as monocots are
arranged in a ring while in monocotyledonous stem they are scattered in general ground tissue
...

2
...


Radial: Separate and alternate strands of phloem and xylem present on different radii
...
@ [Radial = Root]
Conjoint: Xylem and phloem are united and are present on the same radius, e
...
Stem
...
Collateral: Xylem lies towards the inner side and phloem towards the periphery
...
e
...
Dicot
stem
...
,
e
...

Monocot stem
...
Bicollateral: There are two patches of
phloem one on each side of xylem, e
...
stem of Cucurbitaceae
...

i
...
[KU 2014] ii
...


Figure: Different types of vascular bundles A
...
Conjoint collateral C
...

Amphivasal, E
...
Open VB G
...
Hexarch or centripetal xylem I
...
Mesarch xylem

Internal structure of Dicot and Monocot stem:

Figure: Anatomy of Monocot stem and Dicot stem
Dicot stem

Monocot stem

1
...

• Cutinised

• Hairs are generally absent
...
Hypodermis:

• …………………………………………
...
Ground tissue
system:

• Differentiated into hypodermis, • Not differentiated into cortex,
general
cortex,
endodermis,
endodermis and pith
...


4
...
Vascular
bundles:

•
•
•
•
•

6
...
Sec
...

Shape 
Arrangement

• …………………………………………………
[IOM 1998]
•
•
•
•
•

Type
Xylem
No
...


Distinct endodermis and passage cells
...




Figure: T
...
of Root
Difference between anatomy of dicot root and monocot root are:
Dicot Root

Monocot Root

1
...
Cork

• Epiblema, cortex and even • Corks not formed
...

persist

3
...
Endodermal cells later
[NEET 2018]
become highly thickened
...
Pericycle

• Produces lateral roots, cork • Produces lateral roots only
cambium and vascular cambium
Dicot Root
Type
Xylem
No
...
Vascular
bundles

•
•
•
•
•

6
...
Secondary
growth

• Secondary growth present

• Absent

• Xylem and phloem bundles are
polyarch i
...
, > 8
...


Figure: T
...
of leaf


Leaf has upper and lower epidermis, mesophyll and vascular bundle
...
Epidermis:

• • Cuticle
••
Bulliform or motor cells
• absent
•
Hypostomatic
•
•
Guard cell  Kidney-shaped

Cuticle
Bulliform or motor cells present
...
Mesophyll
tissue:

•

Differentiated into palisade •
parenchyma and spongy
parenchyma
...

Bundle sheaths are green and help
in C4 cycle
...
Vascular
bundles:

•

Conjoint, collateral with •
mesarch xylem
Inverted vascular bundles
...

Inverted vascular bundles
...

Lateral
meristem
…………………………………………………………………………………………………………
…………………………………………………………………………………………………………………………………
...

Absent in ………………………………………
...


SECONDARY GROWTH IN DICOT STEMS
Stellar secondary growth
A
...
B in typical dicot stem ……………………………………………………………
...

Inter fascicular cambium ……………………………………………………………
...

B
...
Primary structure, B
...
Formation
of secondary xylem and secondary phloem [NEET 2018]
Cambial cells are of two types-fusiform initials and ray initials
...
e
...

Division of cambial cell Of the two cells formed , one daughter cell remains meristematic
while the other daughter cell becomes permanent
...

[NEET 2017]

•

Cambium ring is more active towards inner side so more secondary xylem cells are formed
...

……………………………………………………………………………………………………………………………………
In autumn  ……………………………………………………………………………………………………… …… … ……
……… …………………………………………………………………………
...

Annual rings are conspicuous in temperate (cold) regions
...
…………………………………………
…………………
...

Color ……………………………………
...




Position ……………………………………
...

[NEET 2017]
Function …………………………………
...


Figure: Heart wood and sap wood in T
...
of old dicot stem

With the passage of time and addition of new outer rings of secondary
xylem more rings of the sap wood are changed into heart wood whereas
the sap wood remains of about the

...
[IOM
2005]

Tyloses are
Bark of Cinchona is source of Quinine (antimalarial drug)

Heart wood of Hematoxylon is source of Hematoxylin (a nuclear dye)

Heart wood of Acacia catechu is source of cutch (katha) used in
coloring clothes and paan
...


Quick Digest:



Figure: Cortical secondary growth
Periderm is made up of three tissues
...
Phellogen (=Cork cambium): It is a secondary lateral meristem that may arise from
hypodermis or outer cortex
...

2
...






Cell walls become thick due to deposition of suberin
...
Phelloderm (=Secondary cortex): Layers of thin walled cells cut-off towards the inner side
of the phellogen form phelloderm
...


Secondary growth in dicot root

Cambium is completely secondary in origin
...

……………………………………………………………………………………………………………………………
...


Cork cambium produces little amount of secondary cortex inwardly and cork cells outwardly

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